Effect of plant architecture on the responses of canopy temperature and water use to population density in winter wheat

Revealing how plant architecture affects the responses of canopy temperature depression (CTD), water use (WU), and grain yield to population density (PD) in wheat (Triticum aestivum L.) would help explore a water-saving pathway related to managing population. This study was conducted over three consecutive years under rainfed and supplemental irrigation conditions. The flat-leafed Jinmai 47 and upright-leafed Jing 411 genotypes were grown at high population density (HD), medium population density (MD), and low population density (LD); seeding rates were 450, 675, and 900 seeds m-2, respectively). CTD peaked at MD in Jinmai 47 but reached the highest at HD in Jing 411. WU generally increased with increasing PD but remained unchanged from LD to MD in Jinmai 47 under the two water conditions, while it remained unchanged from MD to HD under supplemental irrigation condition in Jing 411. Yield increased with increasing density in both genotypes under the two water conditions. It is thus clear that Jinmai 47 gained higher yield but did not consume more water at MD than at LD under the two water conditions; Jing 411 obtained higher yield at the expense of similar amount of water at HD than at MD under supplemental irrigation condition. The grain yield and WU responses of wheat crops to PD implied that through appropriately adjusting PD in combination with plant architecture and water condition, the dual goals of optimizing yield and effectively saving irrigation water could be realized synchronously. Plant architecture influences canopy temperature and water use responses to population density in wheat. Canopy temperature depression reached its peak and then declined with increasing population density in wheat. Water use and grain yield generally increased as sowing density increased from 450 to 900 seeds m-2. Water use did not change at sowing density of 450-675 seeds m-2 for Jinmai 47 and 675-900 seeds m-2 for Jing 411.